Residential air conditioning systems provide refrigeration coils within a plenum of a forced air furnace. The furnace blower circulates air across the refrigeration coils, cooling the air, and distributes the cooled air through the house. As the air is cooled, water in the air may condense onto the refrigeration coils and be conducted to a drain. Thus the air conditioning system both cools and dehumidifies the air of the home.
Normally, in a home system, the dehumidification of air is incidental to the primary objective of cooling the air. Depending on the heat and humidity load imposed by the location and construction of the house itself, the amount of dehumidification will vary considerably. In particular, for a well-insulated house imposing relatively little heat load, the cooling of the air to the desired temperature may be insufficient to remove the humidity present in the house.
In commercial air conditioning systems, both the temperature and the humidity may be controlled by adjusting the compressor speed and/or air speed and by using reheaters which effectively add a heat load to the building. Such systems are relatively expensive and require sophisticated control technology. Further, the ability to control the compressor speed and air flow is not normally available in a residential installation.